Sqlite sqllite中的递归查询CTE

我有下面的表结构。（我是SQL Lite新手）

我想获得Code=4的初始父级： i、 e.值2空B

我不知道如何在sqllite中编写递归查询。 提前感谢..

是版本问题。。 此查询不起作用&出现语法错误。 我从3.7.17升级到了3.8.7.4版本，它运行正常

WITH RECURSIVE
  works(Code,Parent) AS (
   Select Code,ParentCode from Relations a where a.Code=4
    UNION
    SELECT Relations.Code, Relations.ParentCode FROM Relations , works
     WHERE Relations.Code=works.Parent
  )
SELECT * FROM works where Parent is null

你不明白这句话的哪一部分？

WITH RECURSIVE
  works(Code,Parent) AS (
   Select Code,ParentCode from Relations a where a.Code=4
    UNION
    SELECT Relations.Code, Relations.ParentCode FROM Relations , works
     WHERE Relations.Code=works.Parent
  )
SELECT * FROM works where Parent is null